Dimethicones are a series of silicone polymers that contain only M and D units and conform to the structure shown in Figure 1.

Historically, dimethicones are the most understood and commonly used silicone products on the personal care market. They are homopolymers that are insoluble in water and in mineral oil. Dimethicones are also referred to with less technically acceptable terms such as silicone fluids, silicone oils or simply silicones. Dimethicones are sold by viscosity, as seen in Table 1, and vary from low molecular weight, thin materials to thick, sticky products.

Simethicone is an oral anti-foaming agent used to reduce bloating, discomfort and pain caused by excess gas in the stomach or intestinal tract. It is a mixture of polydimethylsiloxane and silica gel, and its structure is shown in Figure 2. There is dimethicone in simethicone, but there is no silica in dimethicone.

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Table 1. Viscosity and molecular weight of dimethicone

Unless dimethicone is blended, its viscosity is directly related to the “n” value and molecular weight.

Viscosity 25°C (Centistokes)

Approximate Molecular Weight

50

3,780

200

9,430

350

13,650

1,000

28,000

60,000

116,500

Figure 1. The structure of dimethicone

Dimethicone is a series of silicone polymers that contain only M and D units and conform to the following structure shown in Figure 1.

Figure 2. The structure of simethicone

Simethicone is an oral anti-foaming agent used to reduce bloating, discomfort and pain caused by excess gas in the stomach or intestinal tract. It is a mixture of polydimethylsiloxane and silica gel, and its structure is shown in Figure 2.